Pseudo-von Willebrand's disease. An intrinsic platelet defect with aggregation by unmodified human factor VIII/von Willebrand factor and enhanced adsorption of its high-molecular-weight multimers.
Four members (from four generations) of a family with a mild bleeding disorder and intermittent thrombocytopenia had decreased plasma levels of properties related to factor VIII/von Willebrand factor (FVIII/VWF), an absence of high-molecular-weight forms of FVIII/VWF in the plasma (but normal multimeric structure in the platelets), and increased ristocetin-induced platelet aggregation, as in Type IIB von Willebrand's disease. However, unlike the abnormality in FVIII/VWF in Type IIB disease, the basic defect in this family was in their platelets, which absorbed FVIII/VWF high-molecular-weight multimers at lower concentrations of ristocetin than did normal platelets. In addition, either in platelet-rich plasma or suspended in buffer, their platelets were aggregated by unmodified normal human FVIII/VWF without ristocetin. Since the abnormalities of plasma FVIII/VWF in this family may be secondary to the platelet abnormalities, the term "pseudo-von Willbrand's disease" may be suitably descriptive of their disorder.
D000327:Adsorption; D000328:Adult; D000368:Aged; D000941:Antigens / Q000032:analysis / Q000502:physiology*; D001779:Blood Coagulation Factors / Q000502:physiology*; D001792:Blood Platelets / Q000032:analysis; D002675:Child, Preschool; D005169:Factor VIII / Q000032:analysis / Q000276:immunology* / Q000502:physiology; D005260:Female; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010974:Platelet Aggregation; D012310:Ristocetin / Q000494:pharmacology; D014842:von Willebrand Diseases / Q000097:blood* / Q000145:classification; D014841:von Willebrand Factor / Q000032:analysis / Q000502:physiology*
D000941:Antigens; D001779:Blood Coagulation Factors; D006023:Glycoproteins; D014841:von Willebrand Factor; D012310:Ristocetin; D005169:Factor VIII